CYLINDER HEADIVALVES
TROUBLESHOOTING
•
Engine top-end problems usually affect engine performance. These problems can
be
diagnosed
by a compression
test
or by tracing top-end noise with a sounding
rod
stethoscope.
•
If the performance
is
poor at low speeds, check
for
white
smoke
in the crankcase
breather
hose.
If t
he
hose
is smoky,
check
for
a seized piston
ring.
Compression too
low,
hard
starting or poor performance at
low
speed
•
Valves:
-
Incorrect valve adjustment
-
Burned
or
bent valves
-
Incorrect
valve
timing
-
Weak valve
spr
ing
-
Uneven
valve
seating
- Valve
stuck open
•
Cylinder
head:
- leaking or damaged cylinder head gasket
-
Warped
or
cracked cylinder
head
•
loose spark
plug
•
Faulty cylinder. piston
or
piston
rings
•
Faulty
decompressor
system
Compression
too
high
•
Excessive
carbon build-up in
cylinde
r
head or
t
op of piston
Excessive smoke
•
Worn valve
stem
or
valve guide
•
Damaged
stem
seal
•
Cylinder, piston or piston rings problem
Excesslv,
noise
•
Incorrect
valve
adjustment
•
Sticking valve or broken valve spring
•
Worn or damaged camshaft
•
Worn
or damaged
valve
lifter
•
Worn or
loose
cam chain
•
Worn
or
damaged cam chain
tensioner
•
Worn
cam
sprocket
teeth
•
Cylinder,
piston or piston rings problem
Rough idle
•
l
ow
cylinder compression
9-6
•